94 GT Pinging & Knocking Noise ~ HELP ~

I have a 1994 Mustang GT 5.0 with a manual transmission. There is a pinging and knocking noise emitting from the engine when you accelerate and everything I have done has not helped! I have had the timing reset (by Ford dealer), new spark plugs, cap, rotor, wires and had the throttle body and injectors cleaned. It does not matter what type or brand of gasoline you run, I've tried just about everyone of them and grades. First thing in the morning (about 5:00 am) it runs okay, but when the engine (or air outside) heats up the worse the pinging and knocking sounds get. It sounds like a bunch of rocks or marbles tumbling around in there.

Any information will be helpful, as I am at the point of putting a new crate engine because the sound is soooo annoying and embarrising while driving. :banghead:

Pull codes!